1. Field of the Invention
This invention relates to cabinets for storing prepared food items and, more particularly, to a cabinet defining a food treatment space within which temperature and/or humidity can be controlled.
2. Background Art
It is the goal of most fast food operators to prepare, and have on hand, food in volumes high enough to promptly accommodate customers during the highest demand hours, yet to minimize waste. These objectives are inherently in competition with each other.
The volume of customers frequenting restaurants cannot be predicted with any certainty. While increase in the volume of customers at peak hours can be anticipated, the volume during these peak hours may vary dramatically from one day to the next, for no apparent reason. For example, large groups often are bussed into fast food restaurants, thereby imposing a severe demand on the food preparers.
To anticipate these unusual demands, fast food owners may keep on hand relatively large quantities of prepared food. A substantial amount of waste inevitably periodically occurs.
The problem of food waste has been significantly diminished by the development of holding cabinets which maintain prepared foods in a cooked and ready-to-eat state for substantial time periods. The assignee herein has made numerous developments in this technology, among which are those described in U.S. Pat. Nos. 4,835,368 and 4,891,498. These units have been highly commercially successful and have demonstrated an ability to maintain the temperature, appearance, taste, texture and aroma of pre-cooked foods for unusually long periods of time.
In each of the systems in the above two patents, a single "environment" with predetermined humidity and temperature parameters is maintained. The units have been provided with an access door which allows introduction of foods into, and removal of foods from, the food treatment space within the cabinet. Certain of these units are equipped with electronic controls to reestablish the desired environment after the doors open and the environment is disturbed.
Food treatment systems which require the development and/or introduction of steam into the food treatment space have some inherent problems. In certain geographic regions the available water supply may have a high chemical content which may corrode even the most expensive and durable metals used in these systems.
These chemicals also tend to accumulate in conduits through which the water is conveyed, oft times detrimentally diminishing the capacity of these conduits and potentially causing a complete blockage thereof. No matter how well a system such as this is designed, these problems cannot be completely avoided.
Another problem with this conventional type cabinet with a single environment is that the access opening to the food treatment space must remain closed to maintain the environment. Users of this type of cabinet are required to open the door each time access to the food treatment space is required, to load and unload foods. Aside from the inconvenience of the food servers having to open the door, the repetitive use of the door may ultimately lead to failure of the hinge and/or latching structure therefor. In some food chains, the assignee herein has determined through its studies that annual repetitions of opening and closing of such closure doors may exceed 1 million. Regardless of how high the quality of the hinge and latch structures is, they are unlikely to withstand such use without some compromise of performance.
Eliminating the door would solve the problems associated with convenience and wear. However, an unobstructed opening in communication with the food treatment space would allow equalization of the humidity and temperature with the outside environment. The only way to avoid this condition with existing systems would be to introduce large quantities of heat and humidity within the food treatment space. Energy requirements for such a system would be prohibitive.
It is known to heat vertically spaced shelves to concentrate heat on foods, as shown in U.S. Pat. No. 4,093,041, to Davis et al. However, the incorporation of the closure doors described therein is a recognition by Davis et al that a closure is necessary to avoid excessive heat loss.